> Let's approach this from a different angle.
Why ? Because the numbers I quoted are consistent and support my opinion ?
> As the coolant cools as
> it passes
> though the radiator it heats the air up to a lower temperature. Thus the air
> passing though the lower part of the radiator absorbs less heat.
The question is, how much less heat. I am suggesting that it is not much less,
that the heat removed by the radiator is primarily limited by the thermal
resistance of the radiator, and the mass (and temperature) of the air flowing
through it ... with the thermostat wide open and the engine running at speed, of
course. Looking at it from an engineer's point of view, the thermal parameters
of the radiator are extremely constrained by space and cost, while using a
bigger water pump is cheap and easy. It just makes sense to run an bigger pump
if that will let you get away with a smaller radiator.
> As the flow through the radiator increases the temperature differential
> decreases and the air passing though the lower part of the radiator
> picks up more
> heat energy and the total amount of cooling increases.
That's true, but it's not a linear relationship, rather it's an asymptotic
curve. I'm suggesting that TR3 cooling systems run well up on that curve, so
are relatively insensitive to small variations in water flow.
> I don't know, I have had no experience with over heating in the TR3 but a
> friend of mine claims that installing a restriction in his bypass solved his
> overheating problem.
Well, all I can say is that I tried it and it made no detectable difference for
me. If it was going to make a difference, I would think the difference would
have to be at idle where water flow is much lower, but a decent fan solved that
problem for me (which again suggests that lack of water flow is not the problem
even at idle).
Are you sure your friend didn't change something else at the same time ?
> It could be significant or else why bother with the skirt on the thermostat?
Could be that someone didn't do their homework, and just assumed that the bypass
had to be blocked. Many if not most cars do not block it ... just look at all
the thermostats at the local parts house that don't have blocking plates on
them. They all have bypasses. And apparently Triumph/BL later decided that it
did not have to be blocked. TR250 & 6 did not, for example. And while the TR7
did (probably due to persistent overheating problems), I suspect the TR8 did
not.
Of course you could settle the argument by taking inlet and outlet water
temperatures on a TR3 running at the brink of thermal overload. Then we could
run them through the calculations I posted before, and see how much difference a
small change in water flow would actually make. Unfortunately I don't have the
means handy to do that ...
Randall
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